Non-destructive layer thickness measurements of multi-layer silicon-on-insulator structures

Layer thickness information on gate and field oxides, buried insulators and epitaxial layers is becoming more critical as device dimensions are reduced and structure complexity increases. Spectroscopic ellipsometry (SE) has been used to measure oxide, epi- and poly-Si thicknesses at stages during processing on structures comprising poly-Si/oxide/SOS and oxide/poly-Si/oxide/bulk Si. The structures measured are directly analogous to multi-layer structures formed during most SOI processing and the applicability to other technologies is illustrated by measurements on commercial SIMOX and ZMR wafers